drivers/net/tokenring: fix sparse warning: cast truncates bits from const value

Impact: Remove the write-only field 'current_ring_status' completely.

Fix this sparse warnings:
  drivers/net/tokenring/smctr.c:4410:52: warning: cast truncates bits from constant value (100 becomes 0)
  drivers/net/tokenring/smctr.c:4415:52: warning: cast truncates bits from constant value (400 becomes 0)
  drivers/net/tokenring/smctr.c:4420:52: warning: cast truncates bits from constant value (800 becomes 0)
  drivers/net/tokenring/smctr.c:4425:52: warning: cast truncates bits from constant value (1000 becomes 0)
  drivers/net/tokenring/smctr.c:4430:52: warning: cast truncates bits from constant value (2000 becomes 0)
  drivers/net/tokenring/smctr.c:4435:52: warning: cast truncates bits from constant value (4000 becomes 0)
  drivers/net/tokenring/smctr.c:4440:52: warning: cast truncates bits from constant value (8000 becomes 0)

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>